Corsac Fox subspecific status in Zoos

Anyone has any clue regarding the subspecific status (Vulpes corsac corsac, V. c. kalmykorum, V. c. turkmenicus), or at least, the geographical origin, of Corsac Foxes (Vulpes corsac) in any zoo? I have not been able to find any reference on this topic.

And apart from the larger body size and denser winter coat (which may be due to Bergmann's rule and climate, not to subspecies), is there any other morphological difference between subspecies? From what I know, there are no skull or genetic analysis which had compared these subspecies, which were establish in 1935 by the Russian zoologist Sergej Ognev.